Ostwald process
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The Ostwald process is an industrial process, invented by Wilhelm Ostwald, used to produce nitric acid.
Following production from the Haber process, ammonia is heated with a catalyst (platinum containing 10% rhodium) to form nitric oxide and water:
- 4 NH3 + 5 O2 → 4 NO + 6 H2O
The nitric oxide is then oxidized to yield nitrogen dioxide:
- 2 NO + O2 → 2 NO2
This in turn reacts with water to yield nitric acid and nitric oxide:
- 4 NO2 + O2 + 2 H2O → 4 HNO3(aq)
The conditions used in industry, which lead to about 96% conversion are:
- pressure between 4 and 10 atmospheres and
- temperatures between 975 and 1125 K.
Fixing nitrogen into ammonia and nitric acid was a key development in the production of fertilisers and explosives. Previously sources of Nitrogen had been Guano and Chilean saltpeter.